Pnictogen–Silicon Analogues of Benzene

Since
the discovery of the first “inorganic benzene”
(borazine, B3N3H6), the synthesis
of other noncarbon derivatives is an ongoing challenge in Inorganic
Chemistry. Here we report on the synthesis of the first pnictogen–silicon
congeners of benzene, the triarsa- and the triphospha-trisilabenzene
[(PhC­(NtBu)2)3Si3E3] (E = P (1a), As (1b)) by
a simple metathesis reaction. These compounds are formed by the reaction
of [Cp″2Zr­(η1:1-E4)]
(E = P, As; Cp″ = C5H3tBu2) with [PhC­(NtBu)2SiCl]
in toluene at room temperature along with the silicon pnictogen congeners
of the cyclobutadiene, [(PhC­(NtBu)2)2Si2E2] (E = P (2a), As
(2b)), which is unprecedented for the arsenic system 2b. All compounds were comprehensively characterized, and
density functional theory calculations were performed to verify the
stability and the aromatic character of the triarsa- and the triphospha-trisilabenzene.